This invention relates to disposable syringes, more specifically, to syringes having a needle protector capable of functioning as a plunger rod after it has been removed from its position protectng the needle and attached to a stopper disposed in the syringe's barrel.
The present invention has several advantages over prior-art syringes wherein the plunger rod/protector is attached at the syringe hub by a force fit over a sheath. The needle is far less likely to be bent during shipment and handling. The syringe barrel is protected at the place where it is most likely to break. The needle sheath will not be removed accidentally when the plunger rod/protector is removed from its protective position. The plunger rod/protector fits well despite normal dimensional variation in a glass syringe barrel.
One aspect of the present invention is a prefilled disposable syringe comprising:
(a) an assembly having a hub, a needle rigidly attached to the hub, and a barrel having a hollow bore and an outer surface near the hub,
(b) a stopper disposed in the bore having first engagement means,
(c) medicament disposed in the bore between the stopper and the needle, and
(d) a plunger rod/protector adapted to enclose the needle, hub and outer surface comprising a narrow portion having a cavity for the needle, the narrow portion capable of fitting within the hollow bore; attachment means for attaching the plunger rod/protector to the outer surface at a first end of the narrow portion comprising an inner surface adapted to enclose the outer surface and flexible means protruding from the inner surface to grip the outer surface; and a second engagement means at a second end of the narrow portion adapted to engage the first engagement means, wherein the plunger rod/protector is adapted to securely protect the needle during transit and storage and to act as a plunger rod after engagement of the first and second engagement means.
Other aspects of the invention comprise a syringe suitable for prefilling and a plunger rod/protector.